M50b28

[BATTS91]

Ive been considering puting the m52b28 crank, pistons and rods in my m50 question 1. Ive been offered a block with internals for£150 plus post is this cheap ??

2. Im on the understanding that the m50 bores may need honing due to a lip ?

3. Do i use bmw Main shells or good aftermarket ones

4 Are arp bolts necessary if i can budget them ??

Anthing else i should know apart from usin m52 loom and ecu???[/list]

[HairyScreech]

A lot of these depend on your opinion and how the donor bits are, so with that in mind:

1. £150 delivered is pretty reasonable provided the internals are usable and its not a lump of scrap.

2. some bores may have a lip some wont. The rule of thumb is if you can feel a lip with your finger nail and it catches on the lip then you need to run a hone down it.
About .007" is the max lip that a ring will skip over.
I had a 4 pot block honed recently for less than £50 for an iron block.

3. Depends how long you want it to last, the m20 i am running atm has good quality aftermarket ones in, its done a HARD 40k now and i can easily see another 60k in it.
If you build with aftermarket ones then you simply have to accept that you wont get the tolerances as tight as stock bmw, with that said they will still be well within reasonable tolerances for an engine.

4. arp bolts wont be needed on a stock rpm limit build.

wouldn't bother with the m52 loom and ecu, just go for the 2.8 injectors and a remap.

[BATTS91]

Well its £150 plus post im awaiting a quote for that ,

Is there any brands you can reccomend on just get onto ecp for shells ? ??

[HairyScreech]

We have been using king bearings in the F4 car, and initially i went "WTF is this shit?" However they have proven to be fine, so i guess its pretty tricky to get bad bearings anymore, just different levels of quality.

In the e30 i used AE/Federal Mogul bearings from a local engine shop. Think they were about £70 but i would have to check.
They were well within acceptable quality.

Have used bmw shells in a mates car, very high quality but outlasted the car they were put into, so make of that what you will. Most of us won't get enough mileage in the remaining life of there car to make it worth it.
If you were really oem anal then go for it.

I wouldn't go to ECP etc for bearings, mostly as they will rip you off, they sell average quality bearings at a premium.
Go to a local engine remanufacturer as they will supply what they use and few builders will use true shite or recommend shite to an enthusiast.
Just take it as a case of the more you pay the higher the tolerances you will get. (ignoring the mark up from the main re-sellers)

In your case i expect a normal high quality aftermarket will do the job just fine, as i doubt you will be expecting 200k from a stroked m50.

[BATTS91]

Well its going to take some abuse lol thats why i asked about oem Shells but if aftermarket are up for the job then £60-80 for them is ok i suppose.

One thing i was thinking is on time saving does the head 100% have to come off or would i be able to get the ol girl on an engine stand and just whip the sump off thats way ?

[BATTS91]

Or is it best to do it the correct way With these engines lol

[HairyScreech]

You won't be able to get the pistons out downwards so it's going to have to come apart.

Unless the shells in it are scrap i would just bung it together with everything from the b28, you will probably want more before it comes apart or wears out.
At which point its time to prep a better/bigger engine.

How long do you realistically expect to run it as a 2.8 before wanting more?

However if you want new shells just chuck a set of aftermarkets in.

If you were going to go for a full nuts and bolts rebuild and fit new rings, get the crank polished etc then it might be worth going for BMW shells, but for what your looking at it would be wasted cash.

[HairyScreech]

However feel free to ignore me as i'm sure someone will be along in the morning to tell you that it will explode and you will die a fiery death if you don't fit BMW parts.

[BATTS91]

How long do you realistically expect to run it as a 2.8 before wanting more?

Now at this point its making me think is the work worth it when i could just get a bare m52 engine bolt my m50 bit on and keep n m50 in the shed for future F/I in a year or 2 when i can afford it :/

[DanThe]

How long do you realistically expect to run it as a 2.8 before wanting more?

Now at this point its making me think is the work worth it when i could just get a bare m52 engine bolt my m50 bit on and keep n m50 in the shed for future F/I in a year or 2 when i can afford it :/

Exactly..

If you must build a 2.8 from the bits id be bolting a freshly serviced head down onto the block your buying, but you'd still need to spend for all the bits you want, when you can buy a running 2.8 for as much/cheaper its a no brainer.
Changing pistons between bores is not worth doing unless your prepared to hone and fit new rings IMO.

As for the management, a proper mapping session of your M50 management will cost a lot more than an M52 loom/ECU, you could even buy a modded loom/remapped/non-EWS ECU from me for less

[maggspower]

@ Screech, King bearings the finish on them is spectacular, bastard file FTW but they work. If you need any honing done in the future give me a shout.

As above Glyco, Fedral Mogal, are the best after market bearings. For OEM expect to pay twice as much, but each bearing size has a further 3 grades within it for perfect tolerances.

Dan is right, pistons from one engine will not be good in another especially if the stroke of the new engine is longer than the one the block came from. A hone, new rings, and broken in correctly, and it will be fine.

[DanThe]

Can you do boring/honing maggspower? Where abouts are you?

[maggspower]

Can you do boring/honing maggspower? Where abouts are you?

Hi Dan, as I'm sure you know honing is just a surface finish no material is removed and yes I can do that, so if the bore is good I can impart the new finish. Thankfuly most BMW engines I come across you can get away with a rehone, I took an M20 apart with over 300000 on it but FSH, the bottom end was all within tolerance, used the pistons again.

The finish grits I have are slightly finer than OEM, and are correct for total seal rings, I have used the finish with standard rings with no ill effects, the rings and bores will actually break in quicker, but "in therory" not last as long, but this is negligable.

I can't do any boring at the moment I have to farm that out to a trusted shop I use. I'm mainly set up for cylinder heads, (found some nice gains for Hairyscreech on his m20b28 quest by regrinding some valves), the tooling and machines are real expensive and I want each machine to pay for the next rather than getting up to my eyeballs........ Its not working at the moment though as the lathe needs a part should have it next week though

I'm in south wales.

[HairyScreech]

If i remember right the block i got for free from Si13 which was a high miler was outside of BMW's anal tolerances, however it was something like 0.035mm max variation across all 6 cylinders, which is still well within tolerance for pretty much any other manufacturer.

Lot of debate over hone grit finish, general consensus seems to be that the engine will finish the cylinders better than anything we can attempt.
Have heard of guys using differing grades to tune the break in conditions to the use of the engine, eg, going finer and running in much harder for race engine to maintain fairly normal run in finish.

Checking the TIS i get:
max ovality 0.03mm
max conicity 0.02mm
Finish 3 to 4 Rt (u)
Bore diameter 84.00 +0.01

For what its worth a 0.05mm tolerance is considered "ok" for most day to day depravity.

[maggspower]

I did a fair amount of research on honing finishing when I was buying tools, all I can say is it is a complete PITA. There are so many conflicting techniques and methods I got sick of looking and instead developed my own opinion.

Honing is all about the peaks and troughs left by the tool, generally speaking the troughs are what we are trying to achieve (to hold an oil film) but they can't be created without peaks as a by product. When you "break in" an engine, that is the action of the rings knocking off these peaks and "seating" itself to the bore. This is where we get "plateau honing" from, a very fine grit or brush is passed over the fresh hone to take these peaks off leaving the troughs untouched, the theory is the engine will then break easily without glazing. Glazing is the bane of breaking a new engine, a shiny bore cannot hold oil instead it will burn it, lose compression and in turn power.

Race engines can use very fine hone finishes, they will break in almost immediatly, and it does not matter if your race engine starts burning oil and losing power at 500 miles if you rebuild it every 400

May aswell have a word on breaking in. Go hard, or go home use cheap mineral oil, 75% of max revs, with plenty of full throttle/high gear, this will push the rings into the bores, followed by over-run to draw oil up the bores to wash away the particals removed. Change oil after 10 miles of this, Go no more than 90% for 500 miles. Oil change. Then go for it

@ Hairyscreech, gonna be building a nice spec 2.7 next month, its got a nice high comp bottom end + a few special bits, I just have to have the crank rebalanced after lightening. I know the spec of the short block, but the head is open to suggestion, so if there is any of your flow bench stuff you would like to try I'm willing to put it up for some research. I'll pm you about it.